Impacts of dams on lowland agriculture in the Mekong River catchment

Sammanfattning: The Mekong River catchment on the Indochinese peninsula in Southeast Asia is currently one of the world’s most active regions in terms of hydropower planning and development. In recent decades China has launched a hydropower plan comprising eight large dams on the main stream river in the upper part of the catchment. Three dams have already been built and now also the countries in the lower basin, Laos, Cambodia and Vietnam have joined the pursuit with great visions. The hydropower expansion may well add to welfare and reduced poverty in especially Laos and Cambodia. However, it might also bring about negative consequences for the people living downstream practicing agriculture on the lowlands adjacent to the river. The purpose of the thesis is to describe if and how agriculture in the lower part of the catchment area is influenced by the impacts of upper catchment dam building. The focal area is the lowland agriculture, i.e. the cultivated floodplains of Laos, Cambodia and the delta in Vietnam. The agricultural practices on the floodplain and in the delta that is said to be impacted by the dam building are rice, riverbank agriculture and aquaculture. Dams in the upper Mekong River were accused for regulating the flows and trapping nutrient-rich sediment. The potential effects of this would e.g. be decline in agricultural productivity and loss of agricultural land. The conclusions are that extended dam development chiefly on the mainstream of the basin will have future negative impact on floodplain agriculture. The most important consequences are the reductions in dry season water flows and trapped sediments. However, up to now there is no definite measurable impact that can be attributed to the dams. Therefore it is important to continue measurements and assessments.